Three-dimensional memory device having a shielding layer and method for forming the same

ABSTRACT

Embodiments of three-dimensional (3D) memory devices having a shielding layer and methods for forming the 3D memory devices are disclosed. In an example, a method for forming a 3D memory device is disclosed. A peripheral device is formed on a first substrate. A first interconnect layer including first interconnect structures are formed above the peripheral device on the first substrate. A shielding layer including a conduction region is formed above the first interconnect layer on the first substrate. The conduction region of the shielding layer covers substantially an area of the first interconnect structures in the first interconnect layer. An alternating conductor/dielectric stack and memory strings each extending vertically through the alternating conductor/dielectric stack are formed on a second substrate. A second interconnect layer including second interconnect structures is formed above the plurality of memory strings on the second substrate. The first substrate and the second substrate are bonded in a face-to-face manner, such that the shielding layer is between the first interconnect layer and the second interconnect layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is division of U.S. application Ser. No. 16/140,427,filed on Sep. 24, 2018, entitled “THREE-DIMENSIONAL MEMORY DEVICE HAVINGA SHIELDING LAYER AND METHOD FOR FORMING THE SAME,” which iscontinuation of International Application No. PCT/CN2018/093423, filedon Jun. 28, 2018, entitled “THREE-DIMENSIONAL MEMORY DEVICE HAVING ASHIELDING LAYER AND METHOD FOR FORMING THE SAME,” both of which arehereby incorporated by reference in their entireties.

BACKGROUND

Embodiments of the present disclosure relate to three-dimensional (3D)memory devices and fabrication methods thereof.

Planar memory cells are scaled to smaller sizes by improving processtechnology, circuit design, programming algorithm, and fabricationprocess. However, as feature sizes of the memory cells approach a lowerlimit, planar process and fabrication techniques become challenging andcostly. As a result, memory density for planar memory cells approachesan upper limit.

A 3D memory architecture can address the density limitation in planarmemory cells. The 3D memory architecture includes a memory array andperipheral devices for controlling signals to and from the memory array.

SUMMARY

Embodiments of 3D memory device having a shielding layer and fabricationmethods thereof are disclosed herein.

In one example, a 3D memory device includes a substrate, a peripheraldevice disposed on the substrate, a plurality of memory strings eachextending vertically above the peripheral device, a semiconductor layerdisposed above and in contact with the plurality of memory strings, anda shielding layer disposed between the peripheral device and theplurality of memory strings. The shielding layer includes a conductionregion configured to receive a grounding voltage during operation of the3D memory device.

In another example, a 3D memory device includes a substrate, a pluralityof memory strings each extending vertically on the substrate, aperipheral device disposed above the plurality of memory strings, asemiconductor layer disposed above and in contact with the peripheraldevice, and a shielding layer disposed between the plurality of memorystrings and the peripheral device. The shielding layer includes aconduction region configured to receive a grounding voltage duringoperation of the 3D memory device.

In a different example, a method for forming a 3D memory device isdisclosed. A peripheral device is formed on a first substrate. A firstinterconnect layer including a first plurality of interconnectstructures are formed above the peripheral device on the firstsubstrate. A shielding layer including a conduction region is formedabove the first interconnect layer on the first substrate. Theconduction region of the shielding layer covers substantially an area ofthe first plurality of interconnect structures in the first interconnectlayer. An alternating conductor/dielectric stack and a plurality ofmemory strings each extending vertically through the alternatingconductor/dielectric stack are formed on a second substrate. A secondinterconnect layer including a second plurality of interconnectstructures is formed above the plurality of memory strings on the secondsubstrate. The first substrate and the second substrate are bonded in aface-to-face manner, such that the shielding layer is between the firstinterconnect layer and the second interconnect layer.

In another example, a method for forming a 3D memory device isdisclosed. An alternating conductor/dielectric stack and a plurality ofmemory strings each extending vertically through the alternatingconductor/dielectric stack are formed on a first substrate. A firstinterconnect layer including a first plurality of interconnectstructures is formed above the plurality of memory strings on the firstsubstrate. A shielding layer including a conduction region is formedabove the first interconnect layer on the first substrate. Theconduction region of the shielding layer covers substantially an area ofthe first plurality of interconnect structures in the first interconnectlayer. A peripheral device is formed on a second substrate. A secondinterconnect layer including a second plurality of interconnectstructures is formed above the peripheral device on the secondsubstrate. The first substrate and the second substrate are bonded in aface-to-face manner, such that the shielding layer is between the firstinterconnect layer and the second interconnect layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate embodiments of the present disclosureand, together with the description, further serve to explain theprinciples of the present disclosure and to enable a person skilled inthe pertinent art to make and use the present disclosure.

FIG. 1A illustrates a cross-section of an exemplary 3D memory devicehaving a shielding layer, according to some embodiments.

FIG. 1B illustrates a cross-section of another exemplary 3D memorydevice having a shielding layer, according to some embodiments.

FIG. 2 illustrates a plan view of an exemplary shielding layer,according to some embodiments.

FIG. 3A illustrates an exemplary layout of a shielding layer, accordingto some embodiments.

FIG. 3B illustrates another exemplary layout of a shielding layer,according to some embodiments.

FIGS. 4A-4D illustrate a fabrication process for forming an exemplaryperipheral device chip, according to some embodiments.

FIGS. 5A-5E illustrate a fabrication process for forming an exemplarymemory array device chip, according to some embodiments.

FIG. 6 illustrates a fabrication process for bonding an exemplary memoryarray device chip and an exemplary peripheral device chip having ashielding layer, according to some embodiments.

FIG. 7 illustrates a fabrication process for bonding another exemplarymemory array device chip having a shielding layer and another exemplaryperipheral device chip, according to some embodiments.

FIG. 8 is a flowchart of a method for forming an exemplary 3D memorydevice having a shielding layer, according to some embodiments.

FIG. 9 is a flowchart of a method for forming another exemplary 3Dmemory device having a shielding layer, according to some embodiments.

Embodiments of the present disclosure will be described with referenceto the accompanying drawings.

DETAILED DESCRIPTION

Although specific configurations and arrangements are discussed, itshould be understood that this is done for illustrative purposes only. Aperson skilled in the pertinent art will recognize that otherconfigurations and arrangements can be used without departing from thespirit and scope of the present disclosure. It will be apparent to aperson skilled in the pertinent art that the present disclosure can alsobe employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “some embodiments,” etc.,indicate that the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of aperson skilled in the pertinent art to effect such feature, structure orcharacteristic in connection with other embodiments whether or notexplicitly described.

In general, terminology may be understood at least in part from usage incontext. For example, the term “one or more” as used herein, dependingat least in part upon context, may be used to describe any feature,structure, or characteristic in a singular sense or may be used todescribe combinations of features, structures or characteristics in aplural sense. Similarly, terms, such as “a,” “an,” or “the,” again, maybe understood to convey a singular usage or to convey a plural usage,depending at least in part upon context. In addition, the term “basedon” may be understood as not necessarily intended to convey an exclusiveset of factors and may, instead, allow for existence of additionalfactors not necessarily expressly described, again, depending at leastin part on context.

It should be readily understood that the meaning of “on,” “above,” and“over” in the present disclosure should be interpreted in the broadestmanner such that “on” not only means “directly on” something but alsoincludes the meaning of “on” something with an intermediate feature or alayer therebetween, and that “above” or “over” not only means themeaning of “above” or “over” something but can also include the meaningit is “above” or “over” something with no intermediate feature or layertherebetween (i.e., directly on something).

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As used herein, the term “substrate” refers to a material onto whichsubsequent material layers are added. The substrate itself can bepatterned. Materials added on top of the substrate can be patterned orcan remain unpatterned. Furthermore, the substrate can include a widearray of semiconductor materials, such as silicon, germanium, galliumarsenide, indium phosphide, etc. Alternatively, the substrate can bemade from an electrically non-conductive material, such as a glass, aplastic, or a sapphire wafer.

As used herein, the term “layer” refers to a material portion includinga region with a thickness. A layer can extend over the entirety of anunderlying or overlying structure or may have an extent less than theextent of an underlying or overlying structure. Further, a layer can bea region of a homogeneous or inhomogeneous continuous structure that hasa thickness less than the thickness of the continuous structure. Forexample, a layer can be located between any pair of horizontal planesbetween, or at, a top surface and a bottom surface of the continuousstructure. A layer can extend horizontally, vertically, and/or along atapered surface. A substrate can be a layer, can include one or morelayers therein, and/or can have one or more layer thereupon, thereabove,and/or therebelow. A layer can include multiple layers. For example, aninterconnect layer can include one or more conductor and contact layers(in which interconnect lines and/or via contacts are formed) and one ormore dielectric layers.

As used herein, the term “nominal/nominally” refers to a desired, ortarget, value of a characteristic or parameter for a component or aprocess operation, set during the design phase of a product or aprocess, together with a range of values above and/or below the desiredvalue. The range of values can be due to slight variations inmanufacturing processes or tolerances. As used herein, the term “about”indicates the value of a given quantity that can vary based on aparticular technology node associated with the subject semiconductordevice. Based on the particular technology node, the term “about” canindicate a value of a given quantity that varies within, for example,10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

As used herein, the term “3D memory device” refers to a semiconductordevice with vertically oriented strings of memory cell transistors(referred to herein as “memory strings,” such as NAND memory strings) ona laterally-oriented substrate so that the memory strings extend in thevertical direction with respect to the substrate. As used herein, theterm “vertical/vertically” means nominally perpendicular to the lateralsurface of a substrate.

In some 3D memory devices, the periphery circuits and memory array arestacked to save wafer area and increase memory cell density. The stackedmemory device architecture often requires additional metal routing, suchas through array contacts (TACs) in memory array, which can result inextra capacitance and resistance. Subsequently, when the noise factorincreases, signals can be distorted and therefore, fail in signalintegrity during transmission. Moreover, coupling effect betweenperiphery circuits and memory array becomes a serious problem as theirmetal interconnects are much closer in a stacked memory devicearchitecture than in a non-stacked architecture, thereby exacerbatingsignal distortion during memory operation.

Various embodiments in accordance with the present disclosure provide a3D memory device having a shielding layer between the stacked peripherycircuits and memory array with a grounding voltage applied on it duringthe memory operation. The grounding voltage applied to the conductivematerials (e.g., metal, metal alloy, metal silicide, dopedsemiconductor, and/or conductive organic material) in the shieldinglayer can shield the transfer of electrical energy between metalinterconnects or any other circuit segments and thus, reduce or evenavoid the coupling effect between the stacked periphery circuits andmemory array in a 3D memory device during its operation.

Moreover, the periphery circuits and memory array can be formed onseparate substrates and later joined by direct bonding. Thede-convolution of the peripheral device processing and memory arrayprocessing from each other can avoid the memory array-induced thermalbudget impact on peripheral devices and improve the performance of theresulting 3D memory device. The shielding layer can be thus formed oneither substrate and include a broad range of conductive materials.

FIG. 1A illustrates a cross-section of an exemplary 3D memory device 100having a shielding layer 102 according to some embodiments of thepresent disclosure. 3D memory device 100 represents an example of anon-monolithic 3D memory device. The term “non-monolithic” means thatthe components of 3D memory device 100 (e.g., peripheral devices andmemory array) can be formed separately on different substrates and thenjoined to form a 3D memory device. 3D memory device 100 can include asubstrate 104, which can include silicon (e.g., single crystallinesilicon), silicon germanium (SiGe), gallium arsenide (GaAs), germanium(Ge), silicon on insulator (SOI), or any other suitable materials.

3D memory device 100 can include a peripheral device on substrate 104.The peripheral device can be formed “on” substrate 104, in which theentirety or part of the peripheral device is formed in substrate 104(e.g., below the top surface of substrate 104) and/or directly onsubstrate 104. The peripheral device can include a plurality oftransistors 106 formed on substrate 104. Isolation regions 108 (e.g.,shallow trench isolations (STIs)) and doped regions (e.g., sourceregions and drain regions of transistors 106) can be formed in substrate104 as well.

In some embodiments, the peripheral device can include any suitabledigital, analog, and/or mixed-signal peripheral circuits used forfacilitating the operation of 3D memory device 100. For example, theperipheral device can include one or more of a page buffer, a decoder(e.g., a row decoder and a column decoder), a sense amplifier, a driver,a charge pump, a current or voltage reference, or any active or passivecomponents of the circuits (e.g., transistors, diodes, resistors, orcapacitors). In some embodiments, the peripheral device is formed onsubstrate 104 using complementary metal-oxide-semiconductor (CMOS)technology (also known as a “CMOS chip”).

3D memory device 100 can include an interconnect layer 110 abovetransistors 106 (referred to herein as a “peripheral interconnectlayer”) to transfer electrical signals to and from transistors 106.Peripheral interconnect layer 110 can include a plurality ofinterconnects (also referred to herein as “contacts”), including lateralinterconnect lines 112 and vertical interconnect access (via) contacts114. As used herein, the term “interconnects” can broadly include anysuitable types of interconnects, such as middle-end-of-line (MEOL)interconnects and back-end-of-line (BEOL) interconnects. Peripheralinterconnect layer 110 can further include one or more interlayerdielectric (ILD) layers (also known as “intermetal dielectric (IMD)layers”) in which interconnect lines 112 and via contacts 114 can form.That is, peripheral interconnect layer 110 can include interconnectlines 112 and via contacts 114 in multiple ILD layers. Interconnectlines 112 and via contacts 114 in peripheral interconnect layer 110 caninclude conductive materials including, but not limited to, tungsten(W), cobalt (Co), copper (Cu), aluminum (Al), silicides, or anycombination thereof. The ILD layers in peripheral interconnect layer 110can include dielectric materials including, but not limited to, siliconoxide, silicon nitride, silicon oxynitride, low dielectric constant(low-k) dielectrics, or any combination thereof.

3D memory device 100 can include a memory array device above theperipheral device. It is noted that x and y axes are added in FIG. 1A tofurther illustrate the spatial relationship of the components in 3Dmemory device 100. Substrate 104 includes two lateral surfaces (e.g., atop surface and a bottom surface) extending laterally in the x-direction(the lateral direction or width direction). As used herein, whether onecomponent (e.g., a layer or a device) is “on,” “above,” or “below”another component (e.g., a layer or a device) of a semiconductor device(e.g., 3D memory device 100) is determined relative to the substrate ofthe semiconductor device (e.g., substrate 104) in the y-direction (thevertical direction or thickness direction) when the substrate ispositioned in the lowest plane of the semiconductor device in they-direction. The same notion for describing spatial relationship isapplied throughout the present disclosure.

In some embodiments, 3D memory device 100 is a NAND Flash memory devicein which memory cells are provided in the form of an array of NANDmemory strings 116 each extending vertically above the peripheral device(e.g., transistors 106) and substrate 104. The memory array device caninclude NAND memory strings 116 that extend vertically through aplurality of pairs each including a conductor layer 120 and a dielectriclayer 122 (referred to herein as “conductor/dielectric layer pairs”).The stacked conductor/dielectric layer pairs are also referred to hereinas an “alternating conductor/dielectric stack” 124. Conductor layers 120and dielectric layers 122 in alternating conductor/dielectric stack 124alternate in the vertical direction. In other words, except the ones atthe top or bottom of alternating conductor/dielectric stack 124, eachconductor layer 120 can be adjoined by two dielectric layers 122 on bothsides, and each dielectric layer 122 can be adjoined by two conductorlayers 120 on both sides. Conductor layers 120 can each have the samethickness or different thicknesses. Similarly, dielectric layers 122 caneach have the same thickness or different thicknesses. Conductor layers120 can include conductor materials including, but not limited to, W,Co, Cu, Al, doped silicon, silicides, or any combination thereof.Dielectric layers 122 can include dielectric materials including, butnot limited to, silicon oxide, silicon nitride, silicon oxynitride, orany combination thereof.

As shown in FIG. 1A, each NAND memory string 116 can include asemiconductor channel 126 and a dielectric layer 128 (also known as a“memory film”). In some embodiments, semiconductor channel 126 includessilicon, such as amorphous silicon, polysilicon, or single crystallinesilicon. In some embodiments, dielectric layer 128 is a composite layerincluding a tunneling layer, a storage layer (also known as “chargetrap/storage layer”), and a blocking layer. Each NAND memory string 116can have a cylinder shape (e.g., a pillar shape). Semiconductor channel126, the tunneling layer, the storage layer, and the blocking layer arearranged along a direction from the center toward the outer surface ofthe pillar in this order, according to some embodiments. The tunnelinglayer can include silicon oxide, silicon oxynitride, or any combinationthereof. The storage layer can include silicon nitride, siliconoxynitride, silicon, or any combination thereof. The blocking layer caninclude silicon oxide, silicon oxynitride, high dielectric constant(high-k) dielectrics, or any combination thereof. In one example, theblocking layer can include a composite layer of silicon oxide/siliconoxynitride/silicon oxide (ONO). In another example, the blocking layercan include a high-k dielectric layer, such as an aluminum oxide(Al₂O₃), or hafnium oxide (HfO₂) or tantalum oxide (Ta₂O₅) layer, and soon.

In some embodiments, NAND memory strings 116 further include a pluralityof control gates (each being part of a word line). Each conductor layer120 in alternating conductor/dielectric stack 124 can act as a controlgate for each memory cell of NAND memory string 116. Each NAND memorystring 116 can include a source select gate at its upper end and a drainselect gate at its lower end. As used herein, the “upper end” of acomponent (e.g., memory NAND string 116) is the end farther away fromsubstrate 104 in the y-direction, and the “lower end” of the component(e.g., NAND memory string 116) is the end closer to substrate 104 in they-direction. For each NAND memory string 116, the source select gate canbe disposed above the drain select gate.

In some embodiments, the memory array device further includes a gateline slit (“GLS”) 130 that extends vertically through alternatingconductor/dielectric stack 124. GLS 130 can be used to form theconductor/dielectric layer pairs in alternating conductor/dielectricstack 124 by a gate replacement process. In some embodiments, GLS 130 isfirstly filled with dielectric materials, for example, silicon oxide,silicon nitride, or any combination thereof, for separating the NANDmemory string array into different regions (e.g., memory fingers and/ormemory blocks). Then, GLS 130 is filled with conductive and/orsemiconductor materials, for example, W, Co, polysilicon, or anycombination thereof, for electrically controlling an array common source(ACS).

In some embodiments, the memory array device further includes word linevia contacts 132 in a staircase structure region of alternatingconductor/dielectric stack 124. Word line via contacts 132 can extendvertically within a dielectric layer. Each word line via contact 132 canhave its upper end in contact with corresponding conductor layer 120 inalternating conductor/dielectric stack 124 to individually address acorresponding word line of the memory array device. In some embodiments,the contact holes and/or contact trenches are also filled with a barrierlayer, an adhesion glue layer, and/or a seed layer besides theconductor.

In some embodiments, the memory array device further includes asemiconductor layer 118 disposed above and in contact with NAND memorystrings 116, for example, on the upper end of each NAND memory string116. Alternating conductor/dielectric stack 124 can be disposed belowsemiconductor layer 118. Semiconductor layer 118 can be a thinnedsubstrate on which the memory array device is formed. In someembodiments, semiconductor layer 118 includes single crystallinesilicon, in which semiconductor layer 118 is referred to as a “singlecrystalline silicon layer.” In some embodiments, semiconductor layer 118can include SiGe, GaAs, Ge, or any other suitable materials.Semiconductor layer 118 can also include isolation regions and dopedregions (e.g., functioning as an array common source for NAND memorystrings 116). Isolation regions (not shown) can extend across the entirethickness or part of the thickness of semiconductor layer 118 toelectrically isolate the doped regions.

Similar to the peripheral device, the memory array device of 3D memorydevice 100 can also include interconnect layers for transferringelectrical signals to and from NAND memory strings 116. As shown in FIG.1A, 3D memory device 100 can include an interconnect layer 134 (referredto herein as an “array interconnect layer”) below NAND memory strings116 and semiconductor layer 118. Array interconnect layer 134 caninclude a plurality of interconnects, including interconnect lines 140and via contacts 142 in one or more ILD layers. In some embodiments, theinterconnects in array interconnect layer 134 include localinterconnects 144 (e.g., bit line via contacts) each having its upperend in contact with the lower end of corresponding NAND memory string116 and its lower end in contact with interconnect line 140 or viacontact 142. Local interconnects 144 can be in contact with thecomponents (e.g., NAND memory strings 116, TACs 146, and GLSs 130) inalternating conductor/dielectric stack 124 directly for fan-out.

Although not shown in FIG. 1A, another interconnect layer (referred toherein as a “BEOL interconnect layer”) can be formed above semiconductorlayer 118 and include interconnects (e.g., interconnect lines and viacontacts) in one or more ILD layers. The BEOL interconnect layer andarray interconnect layer 134 can be formed at opposite sides ofsemiconductor layer 118. In some embodiments, the interconnects in theBEOL interconnect layer can transfer electrical signals between 3Dmemory device 100 and peripheral circuits.

In some embodiments, the memory array device further includes one ormore TACs 146 that extend vertically through alternatingconductor/dielectric stack 124. TAC 146 can extend through the entiretyof alternating conductor/dielectric stack 124, (e.g., all theconductor/dielectric layer pairs therein) and at least part ofsemiconductor layer 118. The upper end of TAC 146 can contact aninterconnect in the BEOL interconnect layer, and the lower end of TAC146 can contact another interconnect 140 or 142 in array interconnectlayer 134. TAC 146 can thus make an electrical connection betweenperipheral interconnect layer 110 and the BEOL interconnect layer andcarry electrical signals from the peripheral device to the BEOLinterconnects of 3D memory device 100.

During the operation of 3D memory device 100 (when 3D memory device 100is in use, for example, performing cell read, write/program, erase,setting, boosting, etc.), coupling effect between the interconnects inperipheral interconnect layer 110 and array interconnect layer 134 cancause signal distortion. To address this problem, as shown in FIG. 1A,3D memory device 100 includes shielding layer 102 between transistors106 and NAND memory strings 116. In some embodiments, shielding layer102 is formed between peripheral interconnect layer 110 and arrayinterconnect layer 134 to reduce the coupling effect between theinterconnects in the adjacent interconnect layers during the operationof 3D memory device 100. As shown in FIG. 1A, peripheral interconnectlayer 110 is disposed between transistors 106 and shielding layer 102,and array interconnect layer 134 is disposed between NAND memory strings116 and shielding layer 102.

Shielding layer 102 can include one or more conduction regions 148 andone or more isolation regions 150. Conduction region 148 can includeconductive materials that have a higher electrical conductivity than anundoped semiconductor material, such as undoped silicon (e.g., amorphoussilicon, single crystalline silicon, or polysilicon). In someembodiments, conduction region 148 has an electrical conductivity of atleast about 1×10⁴ S/m at about 20° C., such as at least 1×10⁴ S/m at 20°C. In some embodiments, conduction region 148 has an electricalconductivity of between about 1×10⁴ S/m and about 1×10⁸ S/m at about 20°C., such as between 1×10⁴ S/m and 1×10⁸ S/m at 20° C. (e.g., 1×10⁴ S/m,1×10⁵ S/m, 5×10⁵ S/m, 1×10⁶ S/m, 2×10⁶ S/m, 3×10⁶ S/m, 4×10⁶ S/m, 5×10⁶S/m, 6×10⁶ S/m, 7×10⁶ S/m, 8×10⁶ S/m, 9×10⁶ S/m, 1×10⁷ S/m, 2×10⁷ S/m,3×10⁷ S/m, 4×10⁷ S/m, 5×10⁷ S/m, 6×10⁷ S/m, 7×10⁷ S/m, 8×10⁷ S/m, 9×10⁷S/m, 1×10⁸ S/m, any range bounded by the lower end by any of thesevalues, or in any range defined by any two of these values, at 20° C.).The conductive materials in conduction region 148 can include, but arenot limited to, metals, metal alloys, metal silicides, dopedsemiconductors, and conductive organic materials. In some embodiments,conduction region 148 includes one or more metals, such as W, Cu, Co,Al, nickel (Ni), and titanium (Ti). Conduction region 148 can alsoinclude any other suitable metals, such as silver (Ag), gold (Au),platinum (Pt), ruthenium (Ru), etc. In some embodiments, conductionregion 148 includes one or more metal alloys, each of which is an alloyof at least two of Cu, Co, Ni, Ti, and W (e.g., TiNi alloy or acombination of TiNi alloy and TiW alloy), or any other suitable metalalloys of, for example, Ag, Al, Au, Pt, iron (Fe), chromium (Cr), etc.In some embodiments, conduction region 148 includes one or more metalsilicides, such as copper silicide, cobalt silicide, nickel silicide,titanium silicide, and tungsten silicide. Conduction region 148 can alsoinclude any other suitable metal silicides, such as silver silicide,aluminum silicide, gold silicide, platinum silicide, etc. In someembodiments, conduction region 148 includes a semiconductor materialdoped with a dopant at a concentration such that the electricalconductivity of conduction region 148 is increased into the rangesdescribed above. In some embodiments, conduction region 148 includes aconductive organic material, such as a conductive polymer, having itselectrical conductivity in the ranges described above.

In some embodiments, shielding layer 102 has a thickness between about 1nm and about 1 μm, such as between 1 nm and 1 μm (e.g., 1 nm, 2 nm, 3nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm,350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm,800 nm, 850 nm, 900 nm, 950 nm, 1 μm, any range bounded by the lower endby any of these values, or in any range defined by any two of thesevalues). In some embodiments, shielding layer 102 has a thicknessbetween about 1 μm and about 20 μm, such as between 1 μm and 20 μm(e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, anyrange bounded by the lower end by any of these values, or in any rangedefined by any two of these values). In some embodiments, shieldinglayer 102 is a compound layer having a plurality of films, such as oneor more conductive films and dielectric films. The thickness rangesdescribed above may refer to the total thickness of a compound shieldinglayer or the thickness of the conductive film(s) in a compound shieldinglayer.

Shielding layer 102 can be patterned to form any suitable layout withdifferent numbers of conduction regions 148 and isolation regions 150 indifferent arrangements. As shown in FIG. 1A, in order to electricallyconnect the stacked memory array device (e.g., NAND memory strings 116)and the peripheral device (e.g., transistors 106) on different planes of3D memory device 100, interconnects are formed between peripheralinterconnect layer 110 and array interconnect layer 134. As a result, 3Dmemory device 100 can include via contacts 152 extending verticallythrough shielding layer 102. Via contact 152 can be in contact with theinterconnects in peripheral interconnect layer 110 and the interconnectsin array interconnect layer 134.

In some embodiments, isolation region 150 extends across the entirethickness of shielding layer 102 to electrically isolate conductionregion 148 and via contacts 152. Isolation region 150 can includedielectric materials including, but not limited to, silicon oxide,silicon nitride, silicon oxynitride, doped silicon oxide, any othersuitable dielectric materials, or any combination thereof. Patterningprocess (e.g., photolithography and dry/wet etch) can be used forpatterning isolation region 150 in shielding layer 102. Isolation region150 then can be formed by thermal growth and/or thin film deposition ofthe dielectric materials in the patterned region.

For example, FIG. 2 illustrates a plan view of an exemplary shieldinglayer 202, according to some embodiments. As shown in FIG. 2, shieldinglayer 202 includes a conduction region 204 and isolation regions 206 forelectrically isolating conduction region 204 and via contacts 208extending through shielding layer 202. Conduction region 204 can coversubstantially the entire area of a substrate 200 except for the areasoccupied by isolation regions 206 and via contacts 208.

In addition to accommodating via contacts 152 through shielding layer102, the layout of shielding layer 102 can vary with respect to the areait covers. For example. FIGS. 3A-3B illustrate exemplary layouts ofshielding layers 302 and 310, according to various embodiments. As shownin FIG. 3A, interconnects 306 and 308 in adjacent interconnect layersare separated vertically by shielding layer 302. A conduction region 304of shielding layer 302 covers substantially the entire area of asubstrate 300 (except for the areas occupied by the isolation regionsand via contacts, not shown) regardless of the layout of interconnects306 and 308. As shown in FIG. 3B, a conduction region 312 of shieldinglayer 310 does not cover substantially the entire area of substrate 300,but instead, covers the area of interconnects 306 and interconnects 308in the adjacent interconnect layers separated by shielding layer 310(e.g., peripheral interconnect layer 110 and array interconnect layer134 in FIG. 1A). It is understood that the layout of a shielding layeris not limited to the examples illustrated above and can vary indifferent embodiments as long as its conduction region covers at leastthe area of interconnects in the adjacent interconnect layers separatedby the shielding layer.

In some embodiments, the area of conduction region 304 (havingconductive materials such as metals) is below 50% of the area ofsubstrate 300 to avoid metal diffusion issue and/or increase thestrength of hybrid bonding between the two semiconductor chips havingthe respective peripheral device and memory array device. That is, thearea of the isolation regions (having dielectric materials such assilicon oxide) is above 50% of the area of substrate 300, according tosome embodiments.

Referring back to FIG. 1A, conduction region 148 of shielding layer 102is configured to receive a grounding voltage during the operation of 3Dmemory device 100. Conduction region 148 can be electrically connectedto a voltage source 154 (or ground) during the operation of 3D memorydevice 100. In some embodiments, the grounding voltage is between about0.1 V and about 50 V, such as between 0.1 V and 50 V (e.g., 0.1 V, 0.2V, 0.3 V, 0.4 V, 0.5 V, 0.6 V, 0.7 V, 0.8 V, 0.9 V, 1 V, 2 V, 3 V, 4 V,5 V, 6 V, 7 V, 8 V, 9 V, 10 V, 15 V, 20 V, 25 V, 30 V, 35 V, 40 V, 45 V,50 V, any range bounded by the lower end by any of these values, or inany range defined by any two of these values). It is understood that thegrounding voltage can be adjusted based on various attributes ofshielding layer 102, such as the thickness and electrical conductivity.During the operation of 3D memory device 100, the grounding voltageapplied to conduction region 148 of shielding layer 102 can reduce (oravoid) the coupling effect between the interconnects in peripheralinterconnect layer 110 and array interconnect layer 134.

A bonding interface A or B can be formed between array interconnectlayer 134 and peripheral interconnect layer 110. In some embodiments,bonding interface A is formed between array interconnect layer 134 andshielding layer 102. In some embodiments, bonding interface B is formedbetween peripheral interconnect layer 110 and shielding layer 102. Asshown in FIG. 1A, the peripheral device (e.g., transistors 106) aredisposed below the memory array device (e.g., NAND memory strings 116)in 3D memory device 100 after bonding.

In some embodiments, a peripheral device chip, including the peripheraldevice (e.g., transistors 106), peripheral interconnect layer 110, andshielding layer 102, is bonded to a memory array device chip, includingNAND memory strings 116 and array interconnect layer 134, in aface-to-face manner at bonding interface A. In some embodiments, aperipheral device chip, including the peripheral device (e.g.,transistors 106) and peripheral interconnect layer 110, is bonded to amemory array device chip, including NAND memory strings 116, arrayinterconnect layer 134, and shielding layer 102, in a face-to-facemanner at bonding interface B. That is, shielding layer 102 can beoverlain on top of either the peripheral device chip or the memory arraydevice chip. The peripheral device chip and the memory array device chipcan be bonded using hybrid bonding (also known as “metal/dielectrichybrid bonding”), which is a direct bonding technology (e.g., formingbonding between surfaces without using intermediate layers, such assolder or adhesives) and can obtain metal-metal bonding anddielectric-dielectric bonding simultaneously. In some embodiments, adielectric film (not shown) is formed on the surface of shielding layer102 at bonding interface A or B to increase the strength of hybridbonding. The dielectric film can be formed between shielding layer 102and peripheral interconnect layer 110 or between shielding layer 102 andarray interconnect layer 134 in FIG. 1A.

FIG. 1B illustrates a cross-section of another exemplary 3D memorydevice 101 having a shielding layer 103, according to some embodimentsof the present disclosure. Similar to 3D memory device 100 describedabove in FIG. 1A, 3D memory device 101 represents an example of anon-monolithic 3D memory device in which a peripheral device chip and amemory array device chip are formed separately and bonded in aface-to-face manner at a bonding interface A or B. Different from 3Dmemory device 100 described above in FIG. 1A in which the peripheraldevice is below the memory array device, 3D memory device 101 in FIG. 1Bincludes a peripheral device disposed above a memory array device. It isunderstood that the details of similar structures (e.g., materials,fabrication process, functions, etc.) in both 3D memory devices 100 and101 may not be repeated below.

3D memory device 101 can include a memory array device on a substrate105. In some embodiments, an array of NAND memory strings 107 eachextends vertically through an alternating conductor/dielectric stack 109on substrate 105. Alternating conductor/dielectric stack 109 can includea plurality of pairs each including a conductor layer 111 and adielectric layer 113. As shown in FIG. 1B, each NAND memory string 107can include a semiconductor channel 115 and a dielectric layer 117 (alsoknown as a “memory film”).

In some embodiments, the memory array device further includes a GLS 119that extends vertically through alternating conductor/dielectric stack109. GLS 119 can be used to form the conductor/dielectric layer pairs inalternating conductor/dielectric stack 109 by a gate replacementprocess. In some embodiments, GLS 119 is filled firstly with dielectricmaterials, for example, silicon oxide, silicon nitride, or anycombination thereof, for separating the NAND memory string array intodifferent regions (e.g., memory fingers and/or memory blocks). In someembodiments, the memory array device further includes word line viacontacts 121 in a staircase structure region of alternatingconductor/dielectric stack 109. Word line via contacts 121 can extendvertically within a dielectric layer. Each word line via contact 121 canhave its lower end in contact with corresponding conductor layer 111 inalternating conductor/dielectric stack 109 to individually address acorresponding word line of the memory array device.

3D memory device 101 can include an interconnect layer 123 above NANDmemory strings 107 (referred to herein as an “array interconnect layer”)to transfer electrical signals to and from NAND memory strings 107.Array interconnect layer 123 can include a plurality of interconnects,including interconnect lines 125 and via contacts 127. In someembodiments, the interconnects in array interconnect layer 123 alsoinclude local interconnects (e.g., bit lines and bit line contacts) eachin contact with the upper end of corresponding NAND memory string 107 toindividually address corresponding NAND memory string 107. In someembodiments, the interconnects in array interconnect layer 123 alsoinclude source lines in contact with the array common sources of NANDmemory strings 107.

3D memory device 101 can include a peripheral device (e.g., transistors131) disposed above the memory array device (e.g., NAND memory strings107). 3D memory device 101 can further include a semiconductor layer 129(e.g., a thinned substrate) disposed above and in contact with theperipheral device (e.g., transistors 131). The entirety or part of theperipheral device can be formed in semiconductor layer 129 (e.g., abovethe bottom surface of semiconductor layer 129) and/or directly belowsemiconductor layer 129. The peripheral device can include a pluralityof transistors 131. Semiconductor layer 129 can be a thinned substrateon which the peripheral device (e.g., transistors 131) is formed. Insome embodiments, semiconductor layer 129 includes single crystallinesilicon, in which semiconductor layer 129 can be referred to as a“single crystalline silicon layer.” In some embodiments, semiconductorlayer 129 can include SiGe, GaAs, Ge, or any other suitable materials.Isolation regions 133 (e.g., STIs) and doped regions (e.g., a sourceregion or a drain region of transistor 131) can be formed insemiconductor layer 129 as well.

Similar to the memory array device, the peripheral device of 3D memorydevice 101 can also include interconnect layers for transferringelectrical signals to and from transistors 131. As shown in FIG. 1B, 3Dmemory device 101 can include an interconnect layer 137 (referred toherein as a “peripheral interconnect layer”) below transistors 131 andsemiconductor layer 129 and also include an interconnect layer (referredto herein as a “BEOL interconnect layer,” not shown) above transistors131 and semiconductor layer 129.

The BEOL interconnect layer can include a plurality of interconnects inone or more ILD layers. In some embodiments, the BEOL interconnect layerincludes any suitable BEOL interconnects that can transfer electricalsignals between 3D memory device 101 and peripheral circuits. Peripheralinterconnect layer 137 can include a plurality of interconnects,including interconnect lines 139 and via contacts 141 in one or more ILDlayers. In some embodiments, the interconnects in peripheralinterconnect layer 137 also include via contacts 135 (e.g., throughsilicon vias (TSVs) if semiconductor layer 129 is a thinned siliconsubstrate) extending vertically through semiconductor layer 129.

During the operation of 3D memory device 101 (when 3D memory device 101is in use, for example, performing cell read, write/program, erase,setting, boosting, etc.), coupling effect between the interconnects inarray interconnect layer 123 and peripheral interconnect layer 137 cancause signal distortion. To address this problem, as shown in FIG. 1B,3D memory device 101 includes shielding layer 103 between NAND memorystrings 107 and the peripheral device (e.g., transistors 131). In someembodiments, shielding layer 103 is formed between array interconnectlayer 123 and peripheral interconnect layer 137 to reduce the couplingeffect between the interconnects in the adjacent interconnect layersduring the operation of 3D memory device 101. As shown in FIG. 1B, arrayinterconnect layer 123 is disposed between NAND memory strings 107 andshielding layer 103, and peripheral interconnect layer 137 is disposedbetween transistors 131 and shielding layer 103.

Shielding layer 103 can include one or more conduction regions 147 andone or more isolation regions 149. Shielding layer 103 can be patternedto form any suitable layout with different numbers of conduction regions147 and isolation regions 149 in different arrangements. As shown inFIG. 1B, in order to electrically connect the stacked memory arraydevice (e.g., NAND memory strings 107) and the peripheral device (e.g.,transistors 131) on different planes of 3D memory device 101,interconnects are formed between array interconnect layer 123 andperipheral interconnect layer 137. As a result, 3D memory device 101 caninclude via contacts 151 extending vertically through shielding layer103. Via contact 151 can be in contact with the interconnects in arrayinterconnect layer 123 and the interconnects in peripheral interconnectlayer 137. In some embodiments, isolation region 149 extends across theentire thickness of shielding layer 103 to electrically isolateconduction region 147 and via contacts 151.

In some embodiments, conduction region 147 of shielding layer 103 isconfigured to receive a grounding voltage during the operation of 3Dmemory device 101. Conduction region 147 can be electrically connectedto a voltage source 153 (or ground) during the operation of 3D memorydevice 101. It is understood that the grounding voltage can be adjustedbased on various attributes of shielding layer 103, such as thethickness and electrical conductivity. During the operation of 3D memorydevice 101, the grounding voltage applied to conduction region 147 ofshielding layer 103 can reduce (or avoid) the coupling effect betweenthe interconnects in array interconnect layer 123 and peripheralinterconnect layer 137. It is understood that other attributes ofshielding layer 103 (and its conduction region 147 and isolation region149) can be similar to those described above with respect to shieldinglayer 102 in FIGS. 1A, 2, and 3A-3B.

A bonding interface A or B can be formed between array interconnectlayer 123 and peripheral interconnect layer 137. In some embodiments,bonding interface A is formed between peripheral interconnect layer 137and shielding layer 103. In some embodiments, bonding interface B isformed between array interconnect layer 123 and shielding layer 103. Asshown in FIG. 1B (and different from FIG. 1A), the peripheral device(e.g., transistors 131) are disposed above the memory array device(e.g., NAND memory strings 107) in 3D memory device 101 after bonding.

In some embodiments, a peripheral device chip, including the peripheraldevice (e.g., transistors 131), peripheral interconnect layer 137, andshielding layer 103, is bonded to a memory array device chip, includingNAND memory strings 107 and array interconnect layer 123, in aface-to-face manner at bonding interface B. In some embodiments, aperipheral device chip, including the peripheral device (e.g.,transistors 131) and peripheral interconnect layer 137, is bonded to amemory array device chip, including NAND memory strings 107, arrayinterconnect layer 123, and shielding layer 103, in a face-to-facemanner at bonding interface A. That is, shielding layer 103 can beoverlain on top of either the peripheral device chip or the memory arraydevice chip. The peripheral device chip and the memory array device chipcan be bonded using hybrid bonding. In some embodiments, a dielectriclayer (not shown) is formed on the surface of shielding layer 103 atbonding interface A or B to increase the strength of hybrid bonding. Thedielectric film can be formed between shielding layer 103 and peripheralinterconnect layer 137 or between shielding layer 103 and arrayinterconnect layer 123 in FIG. 1B.

FIGS. 4A-4D illustrate a fabrication process for forming an exemplaryperipheral device chip, according to some embodiments of the presentdisclosure. FIGS. 5A-5E illustrate a fabrication process for forming anexemplary memory array device chip, according to some embodiments. FIG.6 illustrates a fabrication process for bonding an exemplary memoryarray device chip and an exemplary peripheral device chip having ashielding layer, according to some embodiments. FIG. 7 illustrates afabrication process for bonding another exemplary memory array devicechip having a shielding layer and another exemplary peripheral devicechip, according to some embodiments. FIGS. 8-9 are flowcharts of methodsfor forming exemplary 3D memory devices having a shielding layer,according to various embodiments. Examples of the 3D memory devicedepicted in FIGS. 4-9 include 3D memory device 100 depicted in FIG. 1Aand 3D memory device 101 depicted in FIG. 1B. FIGS. 4-9 will bedescribed together. It is understood that the operations shown inmethods 800 and 900 are not exhaustive and that other operations can beperformed as well before, after, or between any of the illustratedoperations. Further, some of the operations may be performedsimultaneously, or in a different order than shown in FIGS. 8-9.

Referring to FIG. 8, method 800 starts at operation 802, in which aperipheral device is formed on a substrate. Referring to FIG. 9, method900 includes operation 908, in which a peripheral device is formed on asubstrate. The substrate can be a silicon substrate. As illustrated inFIG. 4A, a peripheral device is formed on a silicon substrate 402. Theperipheral device can include a plurality of transistors 404 formed onsilicon substrate 402. Transistors 404 can be formed by a plurality ofprocesses including, but not limited to, photolithography, dry/wet etch,thin film deposition, thermal growth, implantation, chemical mechanicalpolishing (CMP), and any other suitable processes. In some embodiments,doped regions are formed in silicon substrate 402 by ion implantationand/or thermal diffusion, which function, for example, as source regionsand/or drain regions of transistors 404. In some embodiments, isolationregions 406 (e.g., STIs) are also formed in silicon substrate 402 bywet/dry etch and thin film deposition.

Method 800 proceeds to operation 804, as illustrated in FIG. 8, in whichan interconnect layer (e.g., a peripheral interconnect layer) is formedabove the peripheral device. Referring to FIG. 9, method 900 includesoperation 910, in which an interconnect layer (e.g., a peripheralinterconnect layer) is formed above the peripheral device. Theperipheral interconnect layer can include a first plurality ofinterconnects in one or more ILD layers. As illustrated in FIG. 4B, aperipheral interconnect layer 408 can be formed on silicon substrate 402and above transistors 404. Peripheral interconnect layer 408 can includeinterconnects, including interconnect lines 410 and via contacts 412 ofMEOL and/or BEOL in a plurality of ILD layers, to make electricalconnections with the peripheral device (e.g., transistors 404).

In some embodiments, peripheral interconnect layer 408 includes multipleILD layers and interconnects therein formed in multiple processes. Forexample, interconnect lines 410 and via contacts 412 can includeconductive materials deposited by one or more thin film depositionprocesses including, but not limited to, CVD, PVD, ALD, electroplating,electroless plating, or any combination thereof. Fabrication processesto form interconnect lines 410 and via contacts 412 can also includephotolithography, CMP, wet/dry etch, or any other suitable processes.The ILD layers can include dielectric materials deposited by one or morethin film deposition processes including, but not limited to, CVD, PVD,ALD, or any combination thereof. The ILD layers and interconnectsillustrated in FIG. 4B can be collectively referred to as an“interconnect layer” (e.g., peripheral interconnect layer 408).

Method 800 proceeds to operation 806, as illustrated in FIG. 8, in whicha shielding layer is formed above the interconnect layer (e.g., theperipheral interconnect layer). Operation 806 can include forming aconduction region and an isolation region above the peripheralinterconnect layer. The conduction region can cover the area of theinterconnects in the peripheral interconnect layer. In some embodiments,the conduction region of the shielding layer covers substantially thearea of the substrate. Method 800 can further include additionaloperation(s) to form a contact (e.g., via contact) extending verticallythrough the shielding layer and in contact with the interconnects of theperipheral interconnect layer. The contact can be electrically isolatedfrom the conduction region in the shielding layer by the isolationregion.

As illustrated in FIG. 4C, a conductive film 414 can be formed on thetop surface of peripheral interconnect layer 408. The conductivematerials in conductive film 414 can include, but not limited to,metals, metal alloys, metal silicides, doped semiconductors, andconductive organic materials. In some embodiments, conductive film 414includes one or more metals, such as Cu, Co, Ni, Ti, W, or any othersuitable metals. In some embodiments, conductive film 414 includes oneor more metal alloys, each of which is an alloy of at least two of Cu,Co, Ni, Ti, W (e.g., TiNi alloy or a combination of TiNi alloy and TiWalloy), or any other suitable metal alloys. In some embodiments,conductive film 414 includes one or more metal silicides, such as coppersilicide, cobalt silicide, nickel silicide, titanium silicide, tungstensilicide, or any other suitable metal silicides. In some embodiments,conductive film 414 includes one or more doped semiconductors, such asdoped polysilicon, doped amorphous silicon, or any other suitable dopedsemiconductors. In some embodiments, conductive film 414 includes one ormore conductive organic materials, such as conductive polymers, or anyother suitable conductive organic materials.

Conductive film 414 can be formed by one or more thin film depositionprocesses including, but not limited to, CVD, PVD, ALD, electroplating,electroless plating, or any combination thereof. Depending on theconductive materials in conductive film 414, the deposition ofconductive film 414 may involve multiple processes. In some embodiments,the deposition of a metal silicide conductive film involves depositionof a silicon film, deposition of a metal film, and silicidation of thesilicon and metal films by a thermal treatment (e.g., annealing,sintering, or any other suitable processes). In some embodiments, thedeposition of a doped semiconductor conductive film involves depositionof a semiconductor film and doping of the semiconductor film withdopants by ion implantation and/or thermal diffusion. In someembodiments, the deposition of a conductive organic material filminvolves evaporation or solvent-based coating, such as spin-coating andscreen printing.

In some embodiments, deposited conductive film 414 has a thicknessbetween about 1 nm and about 1 μm, such as between 1 nm and 1 μm (e.g.,1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm,250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm,700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1 μm, any range boundedby the lower end by any of these values, or in any range defined by anytwo of these values). In some embodiments, deposited conductive film 414has a thickness between about 1 μm and about 20 μm, such as between 1 μmand about 20 μm (e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19μm, 20 μm, any range bounded by the lower end by any of these values, orin any range defined by any two of these values).

As illustrated in FIG. 4C, a dielectric film 416 can be formed onconductive film 414. Dielectric film 416 can include dielectricmaterials including, but not limited to, silicon oxide, silicon nitride,silicon oxynitride, low-k dielectrics, or any combination thereof.Dielectric film 416 can be formed by thermal growth and/or one or morethin film deposition processes including, but not limited to, CVD, PVD,ALD, or any combination thereof.

As illustrated in FIG. 4D, conductive film 414 can be patterned to forma shielding layer 418 having a conduction region 420 and one or moreisolation regions 422. In some embodiments, conductive film 414 ispatterned to form isolation regions 422, and the remaining conductivematerials in conductive film 414 become conduction region 420.Conduction region 420 and isolation regions 422 can be collectivelyreferred to herein as shielding layer 418. Isolation region 422 caninclude dielectric materials including, but not limited to, siliconoxide, silicon nitride, silicon oxynitride, doped silicon oxide, anyother suitable dielectric materials, or any combination thereof.Patterning process (e.g., photolithography and dry/wet etch) can be usedfor patterning isolation regions 422 in shielding layer 418. Isolationregions 422 can then be formed by thermal growth and/or thin filmdeposition of dielectric materials in the patterned region. Shieldinglayer 418 can be patterned to form any suitable layout in differentarrangements as described above with respect to FIG. 2 and FIGS. 3A-3B.

As illustrated in FIG. 4D, one or more via contacts 424 can be formedthrough dielectric film 416 and shielding layer 418 and in contact withinterconnects 410 and 412 in peripheral interconnect layer 408. Viacontacts 424 can be electrically isolated from conduction region 420 ofshielding layer 418 by isolation regions 422. In some embodiments, viacontacts 424 are formed by first patterning via holes through dielectricfilm 416 and shielding layer 418 using patterning process (e.g.,photolithography and dry/wet etch of dielectric materials in dielectricfilm 416 and conductive materials in shielding layer 418). The via holescan be filled with a conductor (e.g., W). In some embodiments, fillingthe via holes includes depositing a barrier layer, an adhesion layer,and/or a seed layer before depositing the conductor.

Method 800 proceeds to operation 808, as illustrated in FIG. 8, in whichan alternating conductor/dielectric stack and a plurality of memorystrings each extending vertically through the alternatingconductor/dielectric stack are formed on a substrate. Referring to FIG.9, method 900 includes operation 902, in which an alternatingconductor/dielectric stack and a plurality of memory strings eachextending vertically through the alternating conductor/dielectric stackare formed on a substrate. In some embodiments, a contact (e.g., a TAC)extending vertically through the alternating conductor/dielectric stackis formed as well.

As illustrated in FIG. 5A, pairs of first dielectric layer 504 andsecond dielectric layer 506 (referred to herein as “dielectric layerpairs”) are formed on a silicon substrate 502. The stacked dielectriclayer pairs can form an alternating dielectric stack 508. Alternatingdielectric stack 508 can include an alternating stack of firstdielectric layer 504 and second dielectric layer 506 that is differentfrom first dielectric layer 504. In some embodiments, each dielectriclayer pair includes a layer of silicon nitride and a layer of siliconoxide. In some embodiments, first dielectric layers 504 can each havethe same thickness or have different thicknesses. Similarly, seconddielectric layers 506 can each have the same thickness or have differentthicknesses. Alternating dielectric stack 508 can be formed by one ormore thin film deposition processes including, but not limited to, CVD,PVD, ALD, or any combination thereof. In some embodiments, alternatingdielectric stack 508 can be replaced by a plurality ofconductor/dielectric layer pairs, i.e., an alternating stack of aconductor layer (e.g., polysilicon) and a dielectric layer (e.g.,silicon oxide).

As illustrated in FIG. 5B, NAND memory strings 510 are formed on siliconsubstrate 502. Each first dielectric layer 504 of alternating dielectricstack 508 can be replaced by a conductor layer 512, thereby forming aplurality of conductor/dielectric layer pairs in an alternatingconductor/dielectric stack 514. The replacement of first dielectriclayers 504 with conductor layers 512 can be performed by wet/dry etch offirst dielectric layers 504 selective to second dielectric layers 506and filling the structure with conductor layers 512. Conductor layers512 can include conductive materials including, but not limited to, W,Co, Cu, Al, doped silicon, polysilicon, silicides, or any combinationthereof. Conductor layers 512 can be filled by thin film depositionprocesses, such as CVD, ALD, any other suitable process, or anycombination thereof. NAND memory strings 510 can each extend verticallythrough alternating conductor/dielectric stack 514. In some embodiments,conductor layers 512 in alternating conductor/dielectric stack 514 areused to form the select gates and word lines for NAND memory strings510. At least some of conductor layers 512 in alternatingconductor/dielectric stack 514 (e.g., except the top and bottomconductor layers 512) can each be used as word lines of NAND memorystrings 510.

In some embodiments, fabrication processes to form NAND memory string510 further include forming a semiconductor channel 516 that extendsvertically through alternating conductor/dielectric stack 514. In someembodiments, fabrication processes to form NAND memory string 510further include forming a dielectric layer 518 (memory film) betweensemiconductor channel 516 and the plurality of conductor/dielectriclayer pairs in alternating conductor/dielectric stack 514. Dielectriclayer 518 can be a composite dielectric layer, such as a combination ofmultiple dielectric layers including, but not limited to, a tunnelinglayer, a storage layer, and a blocking layer.

The tunneling layer can include dielectric materials including, but notlimited to, silicon oxide, silicon nitride, silicon oxynitride, or anycombination thereof. The storage layer can include materials for storingcharge for memory operation. The storage layer materials can include,but not limited to, silicon nitride, silicon oxynitride, a combinationof silicon oxide and silicon nitride, or any combination thereof. Theblocking layer can include dielectric materials including, but notlimited to, silicon oxide or a combination of silicon oxide/siliconoxynitride/silicon oxide (ONO). The blocking layer can further include ahigh-k dielectric layer, such as an Al₂O₃ layer. Semiconductor channel446 and dielectric layer 448 can be formed by processes such as ALD,CVD, PVD, any other suitable processes, or any combination thereof.

As illustrated in FIG. 5B, a GLS 520 that extends vertically throughalternating conductor/dielectric stack 514 can be formed above siliconsubstrate 502. GLS 520 can include dielectric materials including, butnot limited to, silicon oxide, silicon nitride, silicon oxynitride, orany combination thereof. GLS 520 can be formed by a dry/wet etch processto form a vertical opening through alternating conductor/dielectricstack 514, followed by a fill process to fill the opening withdielectric materials. The opening can be filled by CVD, PVD, ALD, anyother suitable processes, or any combination thereof.

As illustrated in FIG. 5B, word line via contacts 522 are formed abovesilicon substrate 502. Each word line via contact 522 can extendvertically through a dielectric layer. In some embodiments, the lowerend of word line via contact 522 lands on a word line of NAND memorystrings 510 (e.g., conductor layer 512), such that each word line viacontact 522 is electrically connected to corresponding conductor layer512. In some embodiments, fabrication processes to form word line viacontacts 522 include forming a vertical opening using a dry/wet etchprocess, followed by filling the opening with conductor materials andother materials (e.g., a barrier layer, an adhesion layer, and/or a seedlayer) for conductor filling, adhesion, and/or other purposes. Word linevia contacts 522 can include conductive materials including, but notlimited to, W, Co, Cu, Al, doped silicon, silicides, or any combinationthereof. The openings of word line via contacts 522 can be filled withconductive materials and other materials by ALD, CVD, PVD,electroplating, any other suitable processes, or any combinationthereof.

Method 800 proceeds to operation 810, as illustrated in FIG. 8, in whichan interconnect layer (e.g., an array interconnect layer) is formedabove the memory strings. Referring to FIG. 9, method 900 includesoperation 904, in which an interconnect layer (e.g., an arrayinterconnect layer) is formed above the memory strings. The arrayinterconnect layer can include a second plurality of interconnects inone or more ILD layers. As illustrated in FIG. 5C, an array interconnectlayer 524 can be formed above alternating conductor/dielectric stack 514and NAND memory strings 510. Array interconnect layer 524 can includeinterconnects, including interconnect lines 526 and via contacts 528 inone or more ILD layers for transferring electrical signals to and fromNAND memory strings 510.

In some embodiments, array interconnect layer 524 includes multiple ILDlayers and interconnects therein formed in multiple processes. Forexample, interconnect lines 526 and via contacts 528 can includeconductive materials deposited by one or more thin film depositionprocesses including, but not limited to, CVD, PVD, ALD, electroplating,electroless plating, or any combination thereof. Fabrication processesto form interconnect lines 526 and via contacts 528 can also includephotolithography, CMP, wet/dry etch, or any other suitable processes.The ILD layers can include dielectric materials deposited by one or morethin film deposition processes including, but not limited to, CVD, PVD,ALD, or any combination thereof. The ILD layers and interconnectsillustrated in FIG. 5C can be collectively referred to as an“interconnect layer” (e.g., array interconnect layer 524).

Method 900 proceeds to operation 906, as illustrated in FIG. 9, in whicha shielding layer is formed above the interconnect layer (e.g., thearray interconnect layer). Operation 906 can include forming aconduction region and an isolation region above the array interconnectlayer. The conduction region can cover the area of the interconnects inthe array interconnect layer. In some embodiments, the conduction regionof the shielding layer covers substantially the area of the substrate.Method 900 can further include additional operation(s) to form a contact(e.g., via contact) extending vertically through the shielding layer andin contact with the interconnects of the array interconnect layer. Thecontact can be electrically isolated from the conduction region in theshielding layer by the isolation region.

As illustrated in FIG. 5D, a conductive film 530 can be formed on thetop surface of array interconnect layer 524. The conductive materials inconductive film 530 can include, but not limited to, metals, metalalloys, metal silicides, doped semiconductors, and conductive organicmaterials. In some embodiments, conductive film 530 includes one or moremetals, such as Cu, Co, Ni, Ti, W, or any other suitable metals. In someembodiments, conductive film 530 includes one or more metal alloys, eachof which is an alloy of at least two of Cu, Co, Ni, Ti, W (e.g., TiNialloy or a combination of TiNi alloy and TiW alloy), or any othersuitable metal alloys. In some embodiments, conductive film 530 includesone or more metal silicides, such as copper silicide, cobalt silicide,nickel silicide, titanium silicide, tungsten silicide, or any othersuitable metal silicides. In some embodiments, conductive film 530includes one or more doped semiconductors, such as doped polysilicon,doped amorphous silicon, or any other suitable doped semiconductors. Insome embodiments, conductive film 530 includes one or more conductiveorganic materials, such as conductive polymers, or any other suitableconductive organic materials.

Conductive film 530 can be formed by one or more thin film depositionprocesses including, but not limited to, CVD, PVD, ALD, electroplating,electroless plating, or any combination thereof. Depending on theconductive materials in conductive film 530, the deposition ofconductive film 530 may involve multiple processes. In some embodiments,the deposition of a metal silicide conductive film involves depositionof a silicon film, deposition of a metal film, and silicidation of thesilicon and metal films by a thermal treatment (e.g., annealing,sintering, or any other suitable process). In some embodiments, thedeposition of a doped semiconductor conductive film involves depositionof a semiconductor film and doping of the semiconductor film withdopants by ion implantation and/or thermal diffusion. In someembodiments, the deposition of a conductive organic material filminvolves evaporation or solvent-based coating, such as spin-coating andscreen printing.

In some embodiments, deposited conductive film 530 has a thicknessbetween about 1 nm and about 1 μm, such as between 1 nm and 1 μm (e.g.,1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 20 nm, 30nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm,250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm,700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1 μm, any range boundedby the lower end by any of these values, or in any range defined by anytwo of these values). In some embodiments, deposited conductive film 414has a thickness between about 1 μm and about 20 μm, such as between 1 μmand about 20 μm (e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19μm, 20 μm, any range bounded by the lower end by any of these values, orin any range defined by any two of these values).

As illustrated in FIG. 5D, a dielectric film 532 can be formed onconductive film 530. Dielectric film 532 can include dielectricmaterials including, but not limited to, silicon oxide, silicon nitride,silicon oxynitride, low-k dielectrics, or any combination thereof.Dielectric film 532 can be formed by thermal growth and/or one or morethin film deposition processes including, but not limited to, CVD, PVD,ALD, or any combination thereof.

As illustrated in FIG. 5E, conductive film 530 can be patterned to forma shielding layer 534 having a conduction region 536 and one or moreisolation regions 538. In some embodiments, conductive film 530 ispatterned to form isolation regions 538, and the remaining conductivematerials in conductive film 530 become conduction region 536.Conduction region 536 and isolation regions 538 can be collectivelyreferred to herein as shielding layer 534. Isolation region 538 caninclude dielectric materials including, but not limited to, siliconoxide, silicon nitride, silicon oxynitride, doped silicon oxide, anyother suitable dielectric materials, or any combination thereof.Patterning process (e.g., photolithography and dry/wet etch) can be usedfor patterning isolation regions 538 in shielding layer 534. Isolationregions 538 can then be formed by thermal growth and/or thin filmdeposition of dielectric materials in the patterned region. Shieldinglayer 534 can be patterned to form any suitable layout in differentarrangements as described above with respect to FIG. 2 and FIGS. 3A-3B.

As illustrated in FIG. 5E, one or more via contacts 540 can be formedthrough dielectric film 532 and shielding layer 534 and in contact withinterconnects 526 and 528 in array interconnect layer 524. Via contacts540 can be electrically isolated from conduction region 536 of shieldinglayer 534 by isolation regions 538. In some embodiments, via contacts540 are formed by first patterning via holes through dielectric film 532and shielding layer 534 using patterning process (e.g., photolithographyand dry/wet etch of dielectric materials in dielectric film 532 andconductive materials in shielding layer 534). The via holes can befilled with a conductor (e.g., W). In some embodiments, filling the viaholes includes depositing a barrier layer, an adhesion layer, and/or aseed layer before depositing the conductor.

Method 800 proceeds to operation 812, as illustrated in FIG. 8, in whichthe substrate on which the peripheral device is formed and the substrateon which the memory strings are formed are bonded in a face-to-facemanner, such that the shielding layer is between the peripheralinterconnect layer and the array interconnect layer. The bonding can behybrid bonding. In some embodiments, the substrate on which theperipheral device is formed is disposed above the substrate on which thememory strings are formed are the bonding. In some embodiments, thesubstrate on which the peripheral device is formed is disposed below thesubstrate on which the memory strings are formed after the bonding. Inmethod 800, the shielding layer is formed above the peripheralinterconnect layer and peripheral device and is part of the peripheraldevice chip prior to the bonding.

As illustrated in FIG. 6, silicon substrate 502 and components formedthereon (e.g., NAND memory strings 510) are flipped upside down. Arrayinterconnect layer 524 facing down is bonded with dielectric film 416 onshielding layer 418 facing up, i.e., in a face-to-face manner, therebyforming a bonding interface. In some embodiments, a treatment process,e.g., a plasma treatment, a wet treatment, and/or a thermal treatment,is applied to the bonding surfaces prior to the bonding. Although notshown in FIG. 6, silicon substrate 402 and components formed thereon(e.g., transistors 404) can be flipped upside down, and dielectric film416 on shielding layer 418 facing down can be bonded with arrayinterconnect layer 524 facing up, i.e., in a face-to-face manner,thereby forming a bonding interface. After the bonding, via contacts 424through dielectric film 416 and shielding layer 418 are aligned and incontact with corresponding interconnect 526 or 528 in array interconnectlayer 524, so that the interconnects in array interconnect layer 524 areelectrically connected to the interconnects in peripheral interconnectlayer 408. In the bonded device, NAND memory strings 510 can be eitherabove or below the peripheral device (e.g., transistors 404).Nevertheless, in method 800 and FIG. 6, the bonding interface is betweenarray interconnect layer 524 and shielding layer 418.

Method 900 proceeds to operation 912, as illustrated in FIG. 9, in whichthe substrate on which the peripheral device is formed and the substrateon which the memory strings are formed are bonded in a face-to-facemanner, such that the shielding layer is between the peripheralinterconnect layer and the array interconnect layer. The bonding can behybrid bonding. In some embodiments, the substrate on which theperipheral device is formed is disposed above the substrate on which thememory strings are formed after the bonding. In some embodiments, thesubstrate on which the peripheral device is formed is disposed below thesubstrate on which the memory strings are formed after the bonding. Inmethod 900, the shielding layer is formed above the array interconnectlayer and memory strings and is part of the memory array device chipprior to the bonding.

As illustrated in FIG. 7, silicon substrate 502 and components formedthereon (e.g., NAND memory strings 510 and shielding layer 534) areflipped upside down. Dielectric film 532 on shielding layer 534 facingdown is bonded with peripheral interconnect layer 408 facing up, i.e.,in a face-to-face manner, thereby forming a bonding interface. In someembodiments, a treatment process, e.g., a plasma treatment, a wettreatment, and/or a thermal treatment, is applied to the bondingsurfaces prior to the bonding. Although not shown in FIG. 7, siliconsubstrate 402 and components formed thereon (e.g., transistors 404) canbe flipped upside down, and peripheral interconnect layer 408 facingdown can be bonded with dielectric film 532 on shielding layer 534facing up, i.e., in a face-to-face manner, thereby forming a bondinginterface. After the bonding, via contacts 540 through dielectric film532 and shielding layer 534 are aligned and in contact withcorresponding interconnect 410 or 412 in peripheral interconnect layer408, so that the interconnects in array interconnect layer 524 areelectrically connected to the interconnects in peripheral interconnectlayer 408. In the bonded device, NAND memory strings 510 can be eitherabove or below the peripheral device (e.g., transistors 404).Nevertheless, in method 900 and FIG. 7, the bonding interface is betweenperipheral interconnect layer 408 and shielding layer 534.

Although not shown, in some embodiments, the substrate on top of thebonded 3D memory device (e.g., silicon substrate 502 or 402) is thinned,so that the thinned top substrate can serve as a semiconductor layer(e.g., semiconductor layer 118 or 129 in FIGS. 1A-1B), for example, asingle crystalline silicon layer. The thickness of the thinned substratecan be between about 200 nm and about 5 μm, such as between 200 nm and 5μm, or between about 150 nm and about 50 μm, such as between 150 nm and50 μm. The substrate can be thinned by processes including, but notlimited to, wafer grinding, dry etch, wet etch, CMP, any other suitableprocesses, or any combination thereof. In some embodiments, a BEOLinterconnect layer is formed above the semiconductor layer (the thinnedtop substrate). The BEOL interconnect layer can include BEOLinterconnects formed in one or more ILD layers. The BEOL interconnectscan include conductive materials including, but not limited to, W, Co,Cu, Al, doped silicon, silicides, or any combination thereof. The ILDlayers can include dielectric materials including, but not limited to,silicon oxide, silicon nitride, silicon oxynitride, low-k dielectrics,or any combination thereof. In some embodiments, after the bonding andthinning, via contacts (e.g., TSVs) are formed extending verticallythrough the semiconductor layer (the thinned top substrate), for exampleby wet/dry etch followed by depositing conductive materials. The viacontacts can be in contact with the BEOL interconnects in the BEOLinterconnect layer.

In some embodiments, prior to the bonding, a TAC (e.g., TAC 146) isformed extending vertically through alternating conductor/dielectricstack 514 and in contact with the interconnects in array interconnectlayer 524. After the bonding, via contacts can be formed extendingvertically through at least part of the semiconductor layer (the thinnedtop substrate) and in contact with the TAC, so that the BEOLinterconnect layer can be electrically connected to peripheryinterconnect layer 408.

The foregoing description of the specific embodiments will so reveal thegeneral nature of the present disclosure that others can, by applyingknowledge within the skill of the art, readily modify and/or adapt forvarious applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent disclosure. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

Embodiments of the present disclosure have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The Summary and Abstract sections may set forth one or more but not allexemplary embodiments of the present disclosure as contemplated by theinventor(s), and thus, are not intended to limit the present disclosureand the appended claims in any way.

The breadth and scope of the present disclosure should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. A method for forming a three-dimensional (3D)memory device, comprising: forming a peripheral device on a firstsubstrate; forming a first interconnect layer comprising a firstplurality of interconnect structures above the peripheral device on thefirst substrate; forming a shielding layer comprising a conductionregion above the first interconnect layer on the first substrate,wherein the conduction region of the shielding layer coverssubstantially an area of the plurality of interconnect structures in thefirst interconnect layer; forming an alternating conductor/dielectricstack and a plurality of memory strings each extending verticallythrough the alternating conductor/dielectric stack on a secondsubstrate; forming on the second substrate a second interconnect layercomprising a plurality of interconnect structures above the plurality ofmemory strings on the second substrate; and bonding the first substrateand the second substrate in a face-to-face manner, such that theshielding layer is between the first interconnect layer and the secondinterconnect layer.
 2. The method of claim 1, further comprisingforming, prior to bonding the first substrate and the second substrate,a first contact extending vertically through the shielding layer and incontact with the first interconnect layer, wherein the first contact isin contact with the second interconnect layer after bonding.
 3. Themethod of claim 2, wherein forming the shielding layer comprises formingan isolation region in the shield layer to electrically isolate theconduction region and the first contact.
 4. The method of claim 2,further comprising: after bonding the first substrate and the secondsubstrate, thinning the first substrate or the second substrate, so thatthe thinned first or second substrate serves as a semiconductor layer;and forming a third interconnect layer on the semiconductor layer. 5.The method of claim 4, wherein the second substrate is above the firstsubstrate after bonding, and the method further comprises: forming,prior to bonding the first substrate and the second substrate, a secondcontact extending vertically through the alternatingconductor/dielectric stack and in contact with the second interconnectlayer; and forming, after bonding the first substrate and the secondsubstrate, a third contact extending vertically through at least part ofthe semiconductor layer and in contact with the second contact, so thatthe third interconnect layer is electrically connected to the firstinterconnect layer.
 6. The method of claim 4, wherein the firstsubstrate is above the second substrate after bonding, and the methodfurther comprises forming a second contact extending vertically throughthe semiconductor layer and in contact with the third interconnectlayer.
 7. The method of claim 1, wherein the conduction region of theshielding layer covers substantially an area of the substrate.
 8. Themethod of claim 1, further comprising forming, prior to bonding thefirst substrate and the second substrate, a dielectric film on theshielding layer.
 9. A method for forming a three-dimensional (3D) memorydevice, comprising: forming an alternating conductor/dielectric stackand a plurality of memory strings each extending vertically through thealternating conductor/dielectric stack on a first substrate; forming afirst interconnect layer comprising a first plurality of interconnectstructures above the plurality of memory strings on the first substrate;forming a shielding layer comprising a conduction region above the firstinterconnect layer on the first substrate, wherein the conduction regionof the shielding layer covers substantially an area of the firstplurality of interconnect structures in the first interconnect layer;forming a peripheral device on a second substrate; forming a secondinterconnect layer comprising a second plurality of interconnectstructures above the peripheral device on the second substrate; andbonding the first substrate and the second substrate in a face-to-facemanner, such that the shielding layer is between the first interconnectlayer and the second interconnect layer.
 10. The method of claim 9,further comprising forming, prior to bonding the first substrate and thesecond substrate, a first contact extending vertically through theshielding layer and in contact with the first interconnect layer,wherein the first contact is in contact with the second interconnectlayer after bonding.
 11. The method of claim 10, wherein forming theshielding layer comprises forming an isolation region in the shieldlayer to electrically isolate the conduction region and the firstcontact.
 12. The method of claim 10, further comprising: after bondingthe first substrate and the second substrate, thinning the firstsubstrate or the second substrate, so that the thinned first or secondsubstrate serves as a semiconductor layer; and forming a thirdinterconnect layer on the semiconductor layer.
 13. The method of claim12, wherein the first substrate is above the second substrate afterbonding, and the method further comprises: forming, prior to bonding thefirst substrate and the second substrate, a second contact extendingvertically through the alternating conductor/dielectric stack and incontact with the first interconnect layer; and forming, after bondingthe first substrate and the second substrate, a third contact extendingvertically through at least part of the semiconductor layer and incontact with the second contact, so that the third interconnect layer iselectrically connected to the second interconnect layer.
 14. The methodof claim 12, wherein the second substrate is above the first substrateafter bonding, and the method further comprises forming a second contactextending vertically through the semiconductor layer and in contact withthe third interconnect layer.
 15. The method of claim 9, wherein theconduction region of the shielding layer covers substantially an area ofthe substrate.
 16. The method of claim 9, further comprising forming,prior to bonding the first substrate and the second substrate, adielectric film on the shielding layer.